1. Field of the Invention
The present invention relates to a built-in antenna module of a portable wireless terminal and, more particularly, to a method for tuning an antenna module in a portable wireless terminal and built-in antenna module using the same, in which a matching unit is added to facilitate the design of a Planar Inverted-F Antenna (PIFA).
2. Discussion of the Prior Art
Mobile wireless terminals, such as Personal Communication Service (PCS) terminals, Digital Cellular System (DCS) terminals, Global Positioning System (GPS) terminals, Personal Digital Assistants (PDAs), cellular phones and wireless notebooks, are popular and have introduced various functions and designs. New terminals, being introduced, must be small, slim and lightweight. At the same time, the terminals are required to have improved functionality. Therefore, the design of the terminals is focused on size reduction while maintaining or improving the functions demanded by the public.
Today, a rod antenna (also known as a whip antenna) and a helical antenna are widely used owing to their good omnidirectional radiation properties. The rod antenna and the helical antenna protrude outward from the terminal and are easy to break when dropped. This fragility decreases the portability of the terminal. Therefore, a plate type built-in antenna, installed within the terminal, has been widely used in recent times. This arrangement is also called a built-in antenna, internal antenna, or intenna. Various efforts are being made to improve the performance and capability of the built-in antenna.
The built-in PIFA antenna includes a plate type radiator and is electrically connected to a multiple-layer mainboard of a main body of a portable wireless terminal. Also, the PIFA includes two feed lines. One feed line is electrically connected to a feed portion of the mainboard, and the other is electrically connected to a ground portion of the mainboard for grounding. The plate type radiator can function at a desired performance when it is spaced apart from a conductive layer (ground layer) of the mainboard. Therefore, the plate type radiator is mounted on a carrier with a predetermined height to provide separation and then the carrier is mounted on the mainboard.
When designing the PIFA, fixed design parameters and variable design parameters are considered to optimize the performance of the PIFA. Different design parameters may be invoked depending on the requirements necessary to implement various features of the portable wireless terminal. The fixed design parameters, such as radiator length, radiator width, and the distance between the radiator and the ground layer, are firmly fixed depending on the type and size of the portable wireless terminal. Therefore, adjustment of the variable design parameters is important in antenna matching to obtain optimized antenna performance. The variable design parameters may include a feed pin location, feed pin and ground pin widths, the distance between the feed pin and the ground pin, and a pattern configuration formed on the radiator.
However, the tuning of the antenna device using the variable design parameters requires many test samples. Also, since the antenna has to be tested with respect to each variable design parameter, tuning the antenna device is a lengthy process.